1. Technical Field
This disclosure relates to a sheet conveying device to correct positional shifts of a recording medium while the recording medium is traveling in a sheet conveying path, and an image forming apparatus including the sheet conveying device.
2. Related Art
Various types of electrophotographic image forming apparatuses include copiers, printers, facsimile machines, or multifunction machines having two or more of copying, printing, scanning, facsimile, plotter, and other capabilities. Such image forming apparatuses usually include a sheet holding roller that has a stopper (a contact member) attached thereto. The stopper rotates with the sheet holding roller to correct a positional shift and a skew with respect to a sheet conveying direction of a recording medium in a sheet conveying path.
Specifically, in such image forming apparatuses, for example, the sheet holding roller includes two rollers, one of which mounts the stopper thereon to rotate together with the stopper. As the sheet holding roller rotates, the stopper closes the sheet conveying path. With this action, a leading edge of the recording medium that travels in the sheet conveying path contacts the stopper. Consequently, a positional shift in the sheet conveying direction of the recording medium is corrected, which is for convenience referred to as a “positional registration correction”. At the same time, the a positional direction to an oblique side in the sheet conveying direction of the recording medium is corrected, which is for convenience referred to as a “skew correction”. After completion of the positional registration correction and the skew correction, as the sheet holding roller rotates, the stopper opens the sheet conveying path, so that the recording medium further travels toward a downstream side of the sheet conveying path.
As described above, when the positional registration correction and the skew correction are performed, the recording medium contacts the stopper of the sheet holding roller. Impact or shock caused by the contact of the recording medium to the stopper vibrates the stopper in a rotational direction together with the sheet holding roller, and therefore it is likely that the degree of precision of the positional registration correction and the skew correction is reduced.
When the sheet holding roller is driven by gear drive transmission, the stopper easily vibrates in the rotational direction together with the sheet holding roller within a range not exceeding a backlash range.